A device of the above-mentioned type is described in Austrian Patent No. 338 674. In this conventional device, a locking is effected by means of an eccentric arranged in a bearing having a precisely machined bore and a considerable axial length in order to prevent, even after long use of the device, an inclined position of the eccentric shaft. This measure is expensive and requires much work. A further disadvantage of this conventional device is that the locking member is moved into engagement with the serrated edge against the force of the springs, which makes it possible in the case of breakage of the eccentric for the locking member to be lifted automatically out of engagement with the serrated edge.
Another device for facilitating longitudinal adjustment of ski binding parts includes a guide rail which can be secured on a ski, is provided with two lateral guide bars, and has two serrated edges which are arranged between the guide bars and extend in the longitudinal direction of the device, wherein the serrated edges have associated with them a locking member which is biased by at least one helical spring toward the serrated edges, the other end of the helical spring being supported on a bent portion of a guide plate which is movably supported on the guide rail, the ski binding part which is to be adjusted being mounted on the guide plate.
In order to hold the locking member in this device, which has not been disclosed in a printed publication, in a position in which it does not engage the serrated edges, the locking member is provided with lateral shoulders which are held by frictional contact on downward projections of the guide plate, the surfaces on the guide plate which face the shoulders extending, at least over a portion of their length, inclined with respect to a reference normal to the guide plate. Furthermore, in this embodiment, and aside from the guide plate, a special slide plate is also needed which is constructed in one piece with the locking member. All this makes this device somewhat complicated in its design and its manufacture.
It is furthermore suggested in French Patent No. 2 451 756 to equip a heel down-holding arrangement with a device for effecting longitudinal adjustment. In this device, the guide rail is provided with a row of holes which two projections on a locking member can engage in the locked position of the device, the locking member being pressed toward the guide rail by the urging of a helical spring. The locking member is supported, when the ski boot is not inserted, on a downwardly projecting wall of the housing of the heel down-holding arrangement. It is constantly coupled with an approximately U-shaped wire, the web of which extends transversely with respect to the guide rail and is disposed in a recess in the heel holder.
Should the heel down-holding arrangement need to be adjusted along the guide rail, then by means of a special tool in the form of a screwdriver having two grooves which are arranged in the narrow side surfaces of the blade and are directed against the axis of the screwdriver, the wire and thus the locking member are lifted by rotating the screwdriver 90.degree.. The heel down-holding arrangement can thereafter be moved along the guide rail.
When the desired position of the heel down-holding arrangement is reached, the screwdriver is rotated back 90.degree. and thereafter pulled out of engagement with the wire. Through this, and due to the helical spring, the projections on the locking member engage the holes in the guide rail.
This embodiment has the disadvantage that, on the one hand, the heel down-holding arrangement must be specially constructed and that, on the other hand, its adjustment requires a special tool. The solution which is disclosed in the mentioned reference can therefore not be used in general, namely, in connection with a heel holder of any desired type.
A similar embodiment of a heel down-holding arrangement is illustrated in German Offenlegungsschrift No. 30 15 478. In this embodiment, the guide rail is provided with rows of holes which can be engaged by downward projections on a locking member which is pressed toward the guide rail by helical springs. This is brought about by inclined surfaces on the locking member which, when the ski boot is not inserted, rest on corresponding inclined surfaces of the housing of the heel down-holding arrangement.
If the engagement of the locking member and guide rail is to be released, then the locking member is lifted by means of a shoulder which projects rearwardly from the housing of the heel down-holding arrangement and extends parallel to the guide rail in the locking position of the locking member, which causes the projections on the locking member to leave the holes in the guide rail and the heel down-holding arrangement to be able to be moved along the guide rail.
This construction also has the disadvantage that the heel down-holding arrangement must be specially constructed and that, during the adjusting operation, the shoulder of the locking member must always be held, which makes a one-handed adjustment impossible.
Furthermore, it has already been suggested to secure the heel down-holding arrangement on a guide plate which is adjustable along a guide rail provided with a serrated edge and which can be secured by means of a locking member (see for example German Offenlegungsschrift No. 23 42 378). In this design, the engagement of the locking member, which at its end is wedge-shaped, occurs vertically downwardly into the serrated portion, which has upwardly projecting teeth. Furthermore, the engagement takes place under the urging of a compression spring, and thus through a frictional connection, so that during an overload on the adjusting device a change of the adjusted position of the heel down-holding arrangement can occur. This device has an eccentric with two control surfaces which are offset in the axial direction, and the force transfer from the horizontal into the vertical is done through two inclined surfaces. Thus, the known device is complicated in its design and therefore susceptible to breakdown.
A purpose of the invention is to overcome the disadvantages of the known constructions and to provide a device corresponding to the initially mentioned type for facilitating longitudinal adjustment of ski binding parts, which device can be used in heel down-holding arrangements of any desired type of construction, is simple in its design, is inexpensive in its manufacture and reliable in operation, and furthermore can be operated with one hand, whereby as a tool only a conventional commercially available screwdriver is needed.